The U.S. has considered building a fence along its northern border with Canada to keep out terrorists and other criminals, it has emerged.

A Customs and Border Protection Agency report suggested ‘fencing and other barriers’ along the ‘longest non-militarised open border in the world’.

But the U.S. agency has since said it is more concerned about considering the environmental effects of building more infrastructure along the border. A U.S. Customs and Border Protection spokesman said it is not considering the fence option ‘at this time’, reported The Canadian Press.

Its report released last month in Washington D.C. was intended to look at how to tighten the border with Canada to improve security.